Although computers can rapidly process and respond to received data, it is not always possible for certain systems to take advantage of the computer speed. This is particularly true where peripheral devices have very slow response times, or where a system has inherent inertia.
Furnaces and ovens for heating articles at elevated temperatures are generally not precise, nor quick to respond to temperature changes. Furnace systems generally have a high degree of inertia, wherein the heating elements and temperature monitors respond very slowly to external commands. Heating systems, therefore, tend to be difficult to control, and temperature requirements can rarely be held to exacting tolerances.
In recent years, the need to control furnace temperatures to precise and demanding tolerances has become more critical, particularly in the manufacture of semiconductors and detector materials. Such materials generally require prolonged cycles of heating or cooling at precisely held temperatures or temperature gradients, in order that homogeneous, low-defect crystals can be achieved.
The furnace heating and temperature control method of this invention was conceived having as one of its purposes the growth of cadmium telluride and gallium arsenide crystals having uniform properties. One of the heating requirements for obtaining uniform growth for these crystals is the maintenance of a precise temperature and temperature gradients, at close tolerance over an extended period of time during the growth process.
The furnace system of this invention has been designed to be responsive both quickly and accurately to the commands of a computer.
The furnace system of the invention is capable of maintaining and controlling temperatures to precise tolerances, formerly unachievable in the art.